1. Field of the Invention
The present invention relates to nozzles, and more particularly to nozzles for post-mix beverage dispensers. The present invention also relates to methods of mixing liquids by such nozzles.
2. Description of Related Art
In a post-mix beverage dispenser, the constituent ingredients of the beverage, typically two or more liquids, are mixed as they are dispensed through a nozzle. In most instances, one liquid is water saturated with carbon dioxide (usually referred to as soda water or carbonated water) and the other is a flavored syrup. Ideally, the nozzle of a dispenser should deliver a mixed liquid into a container in such a manner that the final beverage is dispensed rapidly, at the proper mixture ratio and temperature, with low foam, and good CO.sub.2 retention, and is thoroughly mixed without stratification of the component liquids.
Many prior nozzles operate satisfactorily at flow rates of approximately three ounces per second. In order to increase the efficiency of the dispenser, it would be advantageous to increase the flow rate to as high as six ounces per second, or more. However, many conventional nozzles have been found to dispense poorer quality beverages having either poor CO.sub.2 retention, high stratification, high foam height or high pressure loss, when subjected to high flow rates.
These deficiencies may be caused by a variety of factors. In addition to mixing the constituent liquids, the beverage dispenser nozzle reduces the high velocity flow from the valve to a very low velocity. However, in many conventional nozzles, the velocity reduction is accompanied by a corresponding pressure loss, which if high, can place significant demands upon the control valves of the dispenser. In addition, rapid pressure loss usually produces turbulence in the soda water, often causing the soda water to lose some carbonation. It has also been found that poor CO.sub.2 retention can result from an abrupt change in the temperature, flow pattern or direction of the soda water.
Further, in a conventional nozzle, syrup is generally introduced into the soda water through four orthogonally directed orifices to increase the mixing of the syrup and soda water. However, because of the relatively high viscosity of the syrup and the small size of the orifices, the syrup often is retained in the orifices after the dispense cycle is completed. Consequently, at the beginning of the next dispense cycle, the retained syrup can be dispensed immediately before the soda water arrives, often resulting in increased stratification (i.e. poor mixing) and spitting of the syrup at the start of the dispense cycle. The force of the individual streams of syrup can also cause CO.sub.2 loss and increased foam height.